How to Size Your Water Lines (PEX & Copper)

Quin Williams of Williams Plumbing shows how to size the water lines in your plumbing system. This method will work for PEX, copper, and galvanized pipes. This video uses the 2018 Uniform Plumbing Code.

0:00 Introduction
1:35 How to calculate the total fixture units
3:12 How to calculate the developed length of the most remote outlet
4:17 How to calculate the elevation of the highest fixture
7:03 The 75% method
7:27 How to size the hot water branch
12:02 How to size the cold water branch
16:07 How to upsize for PEX B
17:07 Please subscribe to see more tutorials!

Williams is the Northwest’s largest plumbing and civil contractor. We offer a comprehensive line of quality plumbing, civil construction, HVAC, green energy, consulting, and service solutions to meet the needs of just about any building project.

Williams Plumbing & Heating, Inc.
2131 Industrial Dr.
Bozeman, MT 59715
[phone]

[willplumb]

This is our first video that uses so many charts and diagrams — did you find our illustrations helpful? What can we do better for future videos? Thanks for watching!

[BrandonHinojosa]

This explanation was perfect. In depth enough without being too repetitive. The charts were fantastic. Really appreciate this video!

[tomrufo]

Hey- this is like the most beautifully put together and well produced educational/informative home improvement video Ive ever seen in YouTube or otherwise. Someone get this guy a full time job doing this.

[beglitchery]

planning on replumbing my 130 yr old home. This is immensely helpful thank you

[nobodynobody]

Wow, you are a life saver. Taking a plumbing class on line and your explanation is pure GOLD. You explain so thoroughly. It has helped me a lot. You are a master teacher. Thank you, thank you!!!!

[richardhy]

A lot goes into these choices. Code is a minimum as you stated, but local codes will also come into play as well as manufacturers recommendations for their faucets (ie.. Grohe brand calls for 3/4” feed on most of their products) which is why you want to have your fixtures picked out before mechanicals are installed so tradesmen know what to prepare for.

[JamesJdoom]

This Video was so good it almost feels illegal. Thank you very much

[chrisboyd]

Remember that this is finding the "minimum" allowed size. You can definitely upsize for more flow. I run at least 3/4" automatically from the water heater all the way to the end of the line and branch off to each fixture with 1/2" .

[djanes]

I love the video and it came at a perfect time for me. I'm sure a lot of people would like to see more videos like this. There really isn't a lot out there explaining how people go about sizing stuff up for their house if they're doing it themselves.

[TerriCull]

Best explanation ever! Thank you so much. I have probably just gotten "lucky" sizing plumbing on rehabs in the past. Now I know I'll be doing the right way!

[grovesville]

I'm an old San Francisco local 38 plumber. Cast iron and copper was the norm there. I did a 4" copper waste (Exposed below) and vent system for the telephone company. Priceless. Nice video and I'm sure you're a top notch plumber. I was! ;-))

[robertjackson]

Excellent video on the whole house plumbing.... Someone installed PEX B at this main coming into the house in a repair but bc you'll never see all the fixtures on at the same time the customer never knew it was done. 99.9% of the time it'll never move 22.25GPM through that point. Copper crimp with no tape/protection buried in the ground.
Thanks again for taking the time and the videographers effort. subbed.

[alwoolhouse]

What a superb, clear, professional presentation. I am just about to plumb an entire off-grid farmhouse with three kitchens & two bathrooms. This was extremely helpful. Thanks.

[FiliAinuu]

that was one of the easiest lesson i've had online great lesson thanks guys

[gypsetsalon]

Awesome as a remodeler I’ve been doing plumbing for yrs and used standard configuration I run the mains as 3/4 then to 1/2. This really opened my eyes to the calculations really needed. Thanx very helpful video

[wyleaziz]

I know now why you said "your favorite plumber". I can not thank you enough for removing such a huuuuge burden regarding pipe sizing and pressure drop. Could you please make a video on how to select the size of the Water heater ( heating element selection) & Water storage tank.. God Bless!

[TrainFlood]

Great tutorial. Very clear and efficient

[MrPerrisin]

I am now a subscriber bro! I’m new to rough in plumbing about a month in and I just about got about all the 3rd&4th guy stuff down backings, scabs, setting tubs, drilling backings, ford fittings for service etc. today when I was in the crawl I had to help the 2nd guy (water piper) tee in some lines and I’m laughing because I think I had that ah ha moment like “oh shit I know how this goes now” anyways dude your video confirmed it and explained so much to me that I felt like I already knew and I’m gonna re watch this video over and over, I’m soooo excited.

Love from Seattle!! 💪🏾

[jtkilroy]

Very helpful, and timely, thanks for putting in that effort

[samwilliams]

Super Helpful THANKS!! As a DIYer it's nice to have a comprehensive how to video and Sweet diagrams!